What is the cementation exponent?

1. n. [Formation Evaluation] The exponent of porosity, m, in the relation of formation factor, F, to porosity, phi. In the Archie equation, F = 1/ phim, H. Guyod termed m the cementation exponent because m was observed to be higher in cemented rock.

What are the factors that affects the cementation exponent?

The grain shape, type of grain, pore structure, specific surface area and compaction are parameters that affect the degree of consolidation called the cementation factor [15].

What is RT in Archie equation?

Rw = formation water resistivity at formation temperature. Φ = porosity. m = cementation exponent, which varies from 1.7 to 3.0 but normally is 2.0. Rt = true resistivity of the formation, corrected for invasion, borehole, thin bed, and other effects.

How do you calculate saturation in water?

Water saturation (Sw) can be measured directly from a sealed core, which is an expensive method, or it can be calculated from the Archie equation, which is less expensive. Sw can also be estimated using a graphical representation of the Archie equation known as the Pickett plot.

What is cementation in sedimentary rocks?

cementation, in geology, hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of a sedimentary rock.

What is formation factor?

Formation factor is the ratio of pore solution conductivity and bulk conductivity of concrete (or the ratio of bulk resistivity to pore solution resistivity, the same thing). Bulk conductivity is the conductivity of concrete as a composite.

What is RT resistivity?

Rw = resistivity of formation water. φ = porosity. Rt = true formation resistivity as derived from a. deep reading resistivity log. Resistivity logs produce a current in the adjacent formation and measure the response of the formation to that current.

Why is Archie’s equation only applicable to sandstone and carbonate?

The Archie equation is valid only when the rock is strongly water wet and clay free, which is not the case in carbonate rocks. There is no linear or direct correlation between resistivity index (IR) and formation water saturation in the carbonate rocks.

How do I calculate saturation?

The natural logarithm of saturation pressure divided by 6.11 raised as a power of e equals the saturation pressure divided by 6.11. Calculate e–a constant that equals 2.71828183–raised to the power of the product from the prior step. Multiply the value of raised e by 6.11 to solve for the saturation pressure.

What is meant by cementation?

Definition of cementation 1 : a process of surrounding a solid with a powder and heating the whole so that the solid is changed by chemical combination with the powder. 2 : the act or process of cementing : the state of being cemented.